1. Technical Field
The present invention relates to a power amplifier that amplifies the power of a drive waveform signal serving as a reference for driving an actuator.
2. Related Art
In known liquid jet printing apparatuses, a liquid is ejected from nozzles by applying a drive signal, the power of which is amplified by a power amplifier, to actuators such as piezoelectric devices. However, when the power of the drive signal is amplified by the use of an analog power amplifier such as a push-pull transistor which is linearly driven, the power loss is great and a large heat sink for heat dissipation is necessary.
JP-A-2005-329710 discloses a technique for reducing the power loss and making a heat sink unnecessary by amplifying the power of a drive signal by the use of a digital power amplifier.
As described in JP-A-2005-329710, when the power of the drive signal is amplified by the use of the digital power amplifier, it is necessary to remove a frequency component of a modulated signal with a low pass filter before amplifying the power. To satisfactorily remove the frequency component of the modulated signals, a low pass filter having a steep frequency characteristic, that is, a high-order low pass filter, for stably transmitting a drive waveform signal component and satisfactorily removing the modulated signal frequency component is necessary. In this case, the potential difference between the terminals of the coil used in the low pass filter increases, leading to a higher hysteresis loss.